A 46-year-old fully active, asymptomatic man suffered two episodes of major peripheral arterial embolism within 2 months. Heart disease was ruled out by appropriate investigations. Further diagnostic evaluation (angiography, CAT scan) revealed the extremely rare finding of a "floating mass" in the transverse aortic arch suspected to be the source of embolization. This mass was successfully removed using the technique of hypothermic cardiocirculatory arrest. The histological diagnosis was an aged intraluminal thrombus and moderate atherosclerosis of the thoracic aorta. For prevention of recurrent arterial embolism in cases without an initially apparent cause and site of origin, a thorough diagnostic, and in a given patient, an aggressive surgical approach for the elimination of the embolic source are advocated.

An increase of arterial carbon dioxide (CO2) partial pressure induces an increase of cerebral blood flow by dilatation of the resistance vessels. By the Transcranial Doppler sonographic technique (TCD) blood flow velocity as a correlate of flow volume can be measured within the great basal intracranial arteries. We investigated 8 patients with an internal carotid artery occlusion or high-grade stenosis and 5 cerebrovascular diseased patients without extracranial stenosis. 12 healthy volunteers and patients without vascular disease served as the control group. Blood flow velocities in the middle cerebral arteries were evaluated before and after 5 minutes of breathing a 5% CO2 gas mixture. In a prestudy the end tidal pCO2 was monitored during this procedure. As a result of the close parallelity of pCO2 increase in the prestudy group we planned to standardize the CO2 reactivity tests without consideration of the individual pCO2 values. The CO2 inhalation provoked a flow velocity increase of at least 20% in the control subjects (47.1 +/- 17.3%). The vascular diseased without extracranial stenosis responded with 34.8 +/- 17.4% (minimum: 23.5%, n. s.). The CO2 reactivity in cases of occlusion or greater than 50% stenosis was significantly decreased (p less than 0.001) both when considering only the affected sides (12.4 +/- 7.5%, maximum: 20%) and when including the non affected sides (22.6 +/- 15.0%). It is concluded that the CO2 reactivity test is a simple and valid method to evaluate the cerebrovascular reserve capacity in any case of uncertainty about the benefits of surgical treatment of a carotid stenosis. In future this technique might become one fundamental argument beside others in selecting adequate treatment.

Circulatory regulation tests--postural heart rate response (PHRR), Valsalva ratio, and reaction to sustained muscle exercise--, sural nerve neurography and cerebral refractory period (CRP) of median nerve evoked potentials were measured in 17 diabetic inpatients and correlated with their clinical signs of autonomic neuropathy (AN) and sensorimotor polyneuropathy (SN). Non-diabetic inpatients (without cardiovascular or related nervous disease) served as controls. The data of the diabetics and non-diabetic age- and sex-matched inpatients were significantly different for the PHHR measured by the 30:15 ratio, sural nerve conduction velocity and sural nerve refractory period, and CRP. The results correlated with the corresponding anamnestic signs. The PHRR showed abnormal values much more frequently than the sural nerve neurography or the CRP. No correlation was found between the signs of AN and those of SN or CRP. This stresses the need for a circulatory regulation test (preferably PHRR) in any diabetic when planning narcosis, as only these AN tests can reliably predict an increased cardiovascular risk in individual patients.

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